Method for treating filaments



Dec. l, 1931. G. E. INMAN ETAL. 1,834,781

METHOD 'FOR TREATING FILAMENTS Filed Deb. 31, 1926 JNMENTUHS:

Patented Dec. 1, 1 931 UNITED STATES PATENT' OFFICE GEORGE E. INMAN, E EAST CLEVELAND, AND'WILLIAH P. ZA'BEL, 0F CLEVELAND y HEIGHTS, OHIO, ASSIGNORS T0 GENERAL ELECTRIC COMPANY, A'O'OBPOBATION 0F v NEW YORK METHOD FOB TBEATING FILAHENTS Applicationdled December 31, 1928. Serial No. 158,374.

V coiled filaments to shape the same from fine Wire, kordinarly tungsten, by coiling around a mandrel w1r e. In some cases th1s 1s a continuous operation and results in the production of a reel of the composite mandrel and coiled filament wire. This is cut up into the requisite lengths and the mandrel wire is dissolved by a suitable chemical leaving the coiled filaments which are then cleaned and given a heat treatment.

a Considerable diiculty has been experi-` enced in handling filament coils during the mandrel dissolving, cleaning and heat treating operations. Heretofore, metal baskets of woven tungsten Wire have been used to carry the coiled filaments through the various dissolving and cleaning baths.- After the drying operation,'thecoiledfilamentshave been taken from the baskets, placed in other "holders known as boats, 'and sent through the firin operation. The basket containers have not en satisfactory on account orf coils tangling with each other and their ends sticking in the meshes of the baskets. Perforated glass tubes have also been used for carrying the coils but they have been unsatisfactory on account of the weakness of the glass.

According to our invention, the filament coils are placed in a container consisting of a tubular coil or spiral of heavywire, preerably tungsten. number 'of comparatively straight sections of coiled filament each containing a mandrel are placed inside the heavy coi ed container. A pair of Vmetal stops are then inserted between turns of the container coil. These serve to confine the filaments in the container and limit their end- Wise movement thereby preventing bending and distortion of them during the treating operations. 'The coiled container is then suspended in the mandrel dissolving and various filament washing and'cleaning solutions as by means of a wire sling having a pair of hooks `which extend through holes formed in the metal stampings. Heretofore, the filament coils, after havingk passed through the mandrel dissolving, washing, cleaning and drying operations, have been taken from their containers and placed in open metal holders,

these holders in turn being inserted in a hy-l drogen furnace for the purpose of firing or annealing. With the type of container such as We have provided the container and filaments therein are placed in the furnace and the coiled filaments are not removed from the container until the treating and firing operation has been completed.

Where the filament coils are produced without a mandrel, the dissolving step is of course unnecessary, but the filament coils may nevertheless be placed lin the container coil to be passed through the cleaning and firing operations..

We have also provided a new and improved type of boat or holder adapted to receive the container coils which are to be placed in the firing or annealing furnace. This has the advantage that the filaments confined in their containers do not come in direct'contact with the holder proper and, moreover, the said filament coils are protected by the holder from falling dust and other foreign material.

A coil or spiral container such as we have provided has many(r advantages over containers heretofore used due to its greater strength `and elasticity, absence of sharp edges or corners and more open space allowing better circulation without the loss of filament coils. With such a container the original straightness of each filament coil is preserved during tainer showing thefilament coils in position between a pair of confining sto s; Fig. 4 is an end view thereof; Fig. 5 is a' ragmentary perspective view of the treating apparatus; Fig. 6 is a perspective, partially broken away, of a centrifugal washing and drying apparatus; Fig. 7 is a perspective of a table for a coil or spiral from heavy acid-resisting,

p-referably tungsten, wire. 1n loading the tube a number of filament coils 11 containing their mandrels are placed inside thereof and confined therein by a 'pair of metal stops, preferably stampings, 12, which are inserted between the coil turns of the tube 1() and held in position by their integral lugs 13. These stops serve to limit any endwise movement of the lament coils, thus prt-)venting any bending and distortion of the said filaments so as to preserve their; original straightness. We prefer to place the stops 12 equidistant from the ends of the tube so as to preserve its balance as it'passes through the various operations during the treatment of the filament coils carried thereby. y

After the tubes have been properly loaded they are transferred to a mandrel dissolving and filament cleaning apparatus shown diagrammatically in Fig. 5. The first ste-p' is to suspend the tube 10 in the mandrel dissolving solution contained in the dish 14, the ffumes of the said solution being drawn into the rectangular flue 15 which is preferably made of wood to withstand chemical action.

- During the dissolving and cleaning operations, the tube 10 is agitated by means of a rocker arm 16 which has extending therefrom a series of hooks 17 each of which carries a tube through a sling 18. The lower portion of the sling comprises a yoke 19 having hook shaped ends 20-21 which engage holes 22 in each of the stops 12. The yoke is made ofhwire such as tungsten and has a single turn spring 23 formed, in it. This prevents the hook shaped ends from being disengaged from the small holes 22 thereby locking the stops in place when the assembly is suspended from the rocker arm 16 as shown. VThe tube 10 is raised and lowered constantly while immersed in the dissolving solution for a defil nite period of time after whichr it is transferred to the next dish 24 which also containsthe same acid dissolving solution as dish 14. All dissolving action in most cases is completed in dish 14, and to insure this, the coils are again immersed in the next dish 24 and any. visible action in this solution indicates that the solution in dish 14 has been too long in use. ,f

The next step is to thoroughly wash the filament @nils so that they may be free from the dissolving acid, and this is accomplished, as before, by suspending `,and agitating the tube 10 in the dish 25. This dish is supplied continuously with hot water by pipe 26.l Following the first washing operation, the filament coils are transferred to the next dish 27 for the purpose of chemical cleaning. During this operation the tube 1() with its content of filament coils is suspended in a cleaning solution contained in the dish 27. Various cleaning solutions 'which are good solvents for metallic oxides may be used, for example, caustic soda, borax ora combination thereof. This solution is kept boiling by means of a burner 28. Additional solution is added from time to time so as to keep a constant 1 supplied to the dish through the pipe 32.h The final hotwater bath is given the filaments as they are suspended in the dish 33 which is also continuously supplied with hot water throu gh the pipe 34. g

After ,passing through the dissolving, cleaning and preliminary washing stages, the tube 10 with its content of lament coils is ready for the final washing and drying stage which is performed vby means of a centrifugal device such as shown 'in Figs. 6 and 7. The

sling 18 is removed from the tube 10 but the stops 12 are retained in their respective places in order that the filaments will lbe properly positioned and confined in the tube during this washing and drying operation. One or Y more tubes of lament coils are placed on a ,table 35 which is mounted on the rotatable spindle 36 of the centrifugal device 37. The

la bath in hot water which is continuously table 35 is held in position on the spindle 36 by means of a pin 38 which ts into the slotted portion 39 of the table. Locateddirectly above the table 35 is alwater tank 40 carried by the housing 41. Before rotating the table 35 the tank 40 is filled with distilled water after which the rotation of the table is begun and when it reaches the proper speed, a plug 42 is lifted through its handle 43 thus allowingthe water to flow upon the said table. The speed of the table is'such as to force the water rapidly through thev tubes and the coils carried thereby. The long orifices 44 located on each side of the table allow the rapid discharge of the flushing water into the housing 41 where it is taken off by means of a drain 45. The housing 41 has a metal lining 46 which takes the wear from grit and dirt thrown out from the rotating t.ble 35 and may be replaced from time to time. The table fed. After the inates strains in the filament wire and removes any impurities present. 4

As the tubes 10 are taken from' the table 35 and prior to firing, the stops 12 are removed and the tubes inserted in the large tubular metal boats 47 shown more particularly in Figs. 8 and 9. These tubular metal holders are then pushed into the heated zone of a furnace (not shown into which hydrogen is laments have been in the heated zone a predetermined time, they are removed to a cooling chamber where they remain for a definite time after which they are poured from the tubes 10.

What we claim as new and desire to secure byLette-rs Patent of the United States, is:

1. The method of treating coiled filaments for electric incandescent lamps and similar articles which consists in packing a quantity of straight lengths of said filaments in a .container having openings therein and confining them so as to prevent endwise movement thereof, and then inserting said container in a cleaning solution to removeimpurities from said filaments.

2. The method of treating coiled filaments for electric incandescent lamps and similar articles which consists in packing a quantity of straight lengths of said filaments in a container having openings therein and confining them so as to prevent endwise movement thereof, then inserting said container in a cleaning solution to remove impurities from said filaments, and afterwards subjecting said filaments to heat without removing them from the said container.

In witness whereof, we have hereunto set our hands this 29th day of December 1926.

GEORGE E. INMAN. WILLIAM P. ZABEL. 

